Syrian-born Olivier Corel, 65, has admitted to The Daily Telegraph that he had been visited on at least one occasion by Merah’s older brother, Abdelkader. But he was evasive when asked if he knew Merah, who this week died in a blaze of gunfire after a 32-hour siege.

Wearing a chequered head scarf that he used to obscure the lower part of his face, and sporting a long beard, he said on Friday that Abdelkader Merah had visited him a few weeks ago to discuss a divorce and Islamist religious law.

Mr Corel, who emigrated to France in 1973 and became a citizen in 1983, was investigated by French police on suspicion of involvement in a circle of jihadists, based in the Ariege region south of Toulouse, and of encouraging them to fight in Iraq.

Several members of the cell were arrested in 2007 in the rural region and were convicted in June 2009 of “association with members of a terrorist organisation.” Mr Corel, who earned his nickname for his fair hair and blonde beard, was not convicted of any offence.

Speaking outside his small holding in the tiny hill-top hamlet of Les Lanes, with the snow-capped Pyrenees as a backdrop, he said: “If he (Abdelkader Merah) says he came by here, then he came by here. People come and go and I cannot tell you all their names.”

His wife Nadia, who wore a veil, repeatedly ordered The Daily Telegraph to stop taking notes of the conversation.

French investigators are trying to establish whether Merah was a self-radicalised “lone wolf” or whether he had accomplices and financial backing.

The interior ministry insists that there is no evidence that he belonged formally to any jihadist group.

But analysts and former intelligence officials have questioned how a young man with no steady job found enough money to buy the small arsenal of weapons that he used to battle police during the drawn-out siege.

Abdelkader Merah, who was also a radical Islamist, made several trips to Cairo, where he stayed in a religious school, according to the French media.

There he developed contacts with Salafist groups. French investigators decided on Friday to keep him, his girlfriend and his mother in custody for another day for questioning.

All three were detained on Wednesday as police surrounded Merah in his apartment in a leafy, middle-class suburb of Toulouse.

Police and prosecution officials have said that traces of what could be an explosive material were found in Abdelkader Merah’s car.

The detainees are being investigated on suspicion of terrorism-related offences.